Method of manufacturing an article and article manufactured by means of the method

ABSTRACT

The invention relates to the manufacture of a platinum pattern on a body, for example, for contacting a semiconductor body. First a layer of a material which can react with the platinum is provided on the body, namely in the form of a negative of the platinum pattern. A layer of platinum is then provided. The pattern of material is caused to react with the platinum layer and the reaction product of the material and the platinum is then removed after which the (positive) platinum pattern remains.

United States Wilting atent 1 1 Dec. 10, 1974 METHOD 01F MANUFACTURINGAN ARTICLE AND ARTICLE MANUFACTURED BY MEANS OF T HE METHOD [75]Inventor: Hermanus Josephus Wilting,

Emmasingel, Eindhoven,

[21] Appl. No.1 312,847

[30] Foreign Application Priority Data Dec. 18, 1971 Netherlands 7117429[52] U.S. Cl 117/212, 156/5, 156/8, 156/17 [51] Int. Cl 344d 1/18, B211)45/00 [58] Field of Search 117/212, 217; 156/3, 7,

[56] References Cited UNITED STATES PATENTS 3,686,080 8/1972 Banfield etal 1. 117/212 Primary Examiner lohn D. Welsh Attorney, Agent, orFirmFrank R. Trifari; Norman N. Spain [57] ABSTRACT The inventionrelates to the manufacture of a platinum pattern on a body, for example,for contacting a semiconductor body. First a layer of a material whichcan react with the platinum is provided on the body, namely in the formof a negative of the platinum pattern. A layer of platinum is thenprovided. The pattern of material is caused to react with the platinumlayer and the reaction product of the material and the platinum is thenremoved after which the (positive) platinum pattern remains.

6 Claims, 5 Drawing Figures METHOD OF MANUFACTURING AN ARTICLE ANDARTICLE MANUFACTURED BY MEANS OF THE METHOD The invention relates to amethod of manufacturing an article in which a platinum layer and a layerof a material which can react with the platinum are provided on a body,parts of the layer of material are removed so as to obtain a pattern ofthe material complementary to the desired platinum pattern, after whichthe platinum of the layer is caused to react with the material of thecomplementary pattern at elevated temperature and the reaction productof the material and the platinum is selectively removed relative to theplatinum so as to obtain the platinum pattern, and to an articlemanufactured by means of the method.

The expression reaction to a reaction product is to be understood tomeanherein not only the chemical reaction of the platinum with thematerial to form a chemical compound, but also, for example, thedissolving or alloying of the platinum and the material to form aproduct which can be selectively removed relative to the platinum. Apattern complementary to the platinum pattern is to be understood tomean herein a pattern which forms a negative relative to the platinumpattern as a positive pattern.

By means of this method, patterns can be obtained in platinum layerswhich cannot be realized, or berealized with difficulty, for example, bymeans of conventional photoetching methods.

The material may often be chosen to be such that the complementarypettern can be obtained in a usual manner, for example,photomechanically.

In a known method of the type mentioned in the preamble (see FrenchPatent Specification No. 2,004,350) the complementary pattern ofmaterial is provided on the platinum layer and, after reaction of thematerial with the platinum layer, the reaction product is removed byetching as a result of which a (positive) platinum pattern remains.

In many applications, in which patterns are to be formed in platinumlayers, not only a platinum layer is provided on the body in addition tothe layer of material, but also layers of other metals, for example,chronium, titanium and/or gold, which in themselves can sometimes beetched better than platinum.

It is of advantage when all the metal layers including the layer ofmaterial, can be provided in one operation, for example, by vapourdeposition.

The drawback is experienced that the material which is providedthroughout the surface reacts with one or more metals differing fromplatinum already during the provision.

It is one of the objects of the invention to avoid the said drawback.The invention is inter alia based on the recognition of the fact thatthe last-mentioned reaction is prevented by providing the material in asearly a stage as possible.

Therefore, the method mentioned in the preamble is characterizedaccording to the invention in that first the complementary pattern ofthe material is provided on the body and then the platinum layer isprovided.

It will be obvious that, since in the method according to the inventionthe material in the complementary pattern is first provided, thematerial can no longer react as the area of the desired pattern withafter metal layers to be provided afterwards.

In the method according to the invention the material must of course beselectively removable relative to the body. As already stated above, theremoval of the reac tion product can be carried out by selectiveetching.

In a preferred embodiment of the method according to the invention,however, the reaction product is selectively removed relative to theplatinum by means of an ultrasonic method. reaction product often ismuch more brittle than the original platinum, as a result of whichmechanical methods of removing, for example, the ultrasonic method, isselective particularly in the method according to the invention.

Further it may be noted that combinations of the removal methods, suchas etching and ultrasonic operation, are possible.

The material is preferably chosen from at least one element belonging tothe group consisting of the elements of the groups IIIB and [VB of theperiodic table.

In a variation of the method according to the invention the materialshosen is germanium. A layer of titanium or chromium is preferablypresent between the layer of platinum and the body.

The invention furthermore relates to an aticle, in particular asemiconductor device, manufactured by means of the method according tothe invention.

The invention will now be described in greater detail with reference toa drawing and a few examples.

FIGS. 1 to 5 are diagrammatic cross-sectional views of a part of anarticle in successive stages of manufacture by means of the methodaccording to the invention.

In the following example, a layer 2 of germanium is provided on asilicon body 1 (FIG. 1). Germanium can react with platinum. Parts'of thegermanium layer 2 are removed so as to obtain a germanium pattern whichis complementary to the desired platinum pattern (FIG. 2). A chromiumlayer 4 and a platinum layer 5 are then provided on the complementarygermanium pattern (FIG. 3) and the platinum is caused to react with thegermanium to form a reaction product 6 (FIG.

The reaction product 6 of the germanium and the platinum is selectivelyremoved relative to the metal to obtain the platinum pattern (FIG. 5).

The germanium layer 2 is provided, for example, by vapour deposition andis approximately 0.1 u thick.

The complementary germanium pattern is obtained in a usual manner bymeans of a photoetching method, in which a photolacquer layer is usedasan etching mask for etching germanium in a bath containing hydrogenperoxide and, possibly, hydrofluoric acid.

The layers 4 and 5 are also provided by vapour deposition. The chromiumlayer is approximately 500 A thick and the platinum layer 5 isapproximately 0.15 ,u thick. The temperature of the body 1 during thevapour deposition process is approximately 450C the platinum diffusingthrough the thin chromium layer 4 and reacting with the underlyinggermanium. The reaction product of germanium and platinum is removed bydipping the body in aqua regia. The reaction project GePt dissolves init many times faster than platinum alone. The reaction product may alsobe removed ultrasonically.

The chromium layer 4 serves to obtain a good adherence between theplatinum layer 5 and the silicon body I. With the said chromium layer 4,a reaction in the lateral direction is also prevented, as a result ofwhich a good edge sharpness of the platinum pattern is obtained.

With the layers 4 and 5 which need not everywhere adjoin directly thesilicon but-may be separated from it, for example, by an insulatingoxide layer, regions of the silicon body can be contacted on the onehand, and on the other hand the platinum layer may be used forcontacting connection conductors.

The platinum layer is preferably fortified with gold, for example,electrolytically, and titanium is used as an adhering layer instead ofchromium. The contacting of a semiconductor body to obtain asemiconductor device may be carried out by:

a. alloying a silicon body via apertures in an oxide layer withplatinum;

b. removing the non-reacted platinum on the oxide layer;

0. vapour-depositing a germanium layer on the semiconductor body;

d. providing the complementary pattern in the germanium layer;

e. vapour-depositing a thin titanium layer, a platinum layer and a thingold layer;

f. reacting the metal layers with the germanium layer to form a reactionproduct;

g. locally electrolytically thickening the gold layer;

h. removing the reaction product. The reaction product may be etchedaway, but, owing to its brittle character, it may also be removedultrasonically.

The method according to the invention is not re- 1 stricted to theexamples described but may be varied in many ways.

For example, the method is not restricted to the manufacture ofsemiconductor devices but in general arti- Instead of germanium, thematerial used may be, for

example, silicon, but also an element from the group 1113 or IVB of theperiodic table, for example, aluminum, may be used.

What is claimed is:

1. A method of providing a platinum pattern on a substrate said methodcomprising providing, in a pattern complementary to the desired platinumpattern, a layer of a material reactive with platinum on a substrateproviding a layer of platinum on said material and on the exposedportions of the substrate, forming a reaction product of platinum andthe material of the complementary pattern and selectively removing thereaction product of the platinum and the material from the body relativeto the platinum thereby leaving the desired platinum pattern on thebody.

2. A method as claimed in claim 1, wherein the reaction product isselectively removed relative to the platinum by means of ultrasonicenergy.

3. A method as claimed in claim 1, wherein the mate rial is chosen fromat least one element belonging to the group consisting of the elementsof groups [H8 and W8 of the periodic table.

4. A method as claimed in claim 3, wherein the material chosen isgermanium.

5. A method as claimed in claim 3, wherein a layer of titanium orchromium is present between the layer of platinum and the substrate.

6. A method as claimed in claim 1 wherein a layer of gold is provided onthe platinum.

l l i Patent No. 3,853,613 Dated December 10 1974 h IG Inventor(s) It iscertified that error appears in the above-iclentified patent and thatsaid Letters Patent are hereby corrected as shown below:

In the title page, under [75] Inventors" change "Hermanus Josephuswilting" to Hermanus Josephus Henricus Wilting Signed an fiealcd thistwenty-ninth Day Of July 1975 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting ()jjicer (mnmisxiumr uj'luu'msand Trademarks-

1. A METHOD OF PROVIDING A PLATINUM PATTERN ON A SUBSTRATE SAID METHODCOMPRISING PROVIDING, IN A PATTERN COMPLEMENTARY TO THE DESIRED PLATINUMPATTERN, A LAYER OF A MATERIAL REACTIVE WITH PLATINUM ON A SUBSTRATEPROVIDING A LAYER OF PLATINUM ON SAID MATERIAL AND ON THE EXPOSEDPORTIONS OF THE SUBSTRATE, FORMING A REACTION PRODUCT OF PLATINUM ANDTHE MATERIAL OF THE COMPLEMENTARY PATTERN AND SELECTIVELY REMOVING THEREACTION PRODUCT OF THE PLATINUM AND THE MATERIAL FROM THE BODY RELATIVETO THE PLATINUM THEREBY LAEVING THE DESIRED PLATINUM PATTERN ON THEBODY.
 2. A method as claimed in claim 1, wherein the reaction product isselectively removed relative to the platinum by means of ultrasonicenergy.
 3. A method as claimed in claim 1, wherein the material ischosen from at least one element belonging to the group consisting ofthe elements of groups IIIB and IVB of the periodic table.
 4. A methodas claimed in claim 3, wherein the material chosen is germanium.
 5. Amethod as claimed in claim 3, wherein a layer of titanium or chromium ispresent between the layer of platinum and the substrate.
 6. A method asclaimed in claim 1 wherein a layer of gold is provided on the platinum.